1. Field of the Invention
Embodiments described herein relate generally to a charged particle beam lithography apparatus, an inspection method, and an inspection apparatus of pattern writing data and, for example, relate to a technique of inspecting input data into a lithography apparatus for abnormalities
2. Related Art
A lithography technique which leads development of micropatterning of a semiconductor device is a very important process for exclusively generating a pattern in semiconductor manufacturing processes. In recent years, with an increase in integration density of an LSI, a circuit line width required for semiconductor devices is getting smaller year by year. In order to form a desired circuit pattern on such semiconductor devices, a high-precision original pattern (also called a reticle or a mask) is needed. In this case, an electron beam pattern writing technique has an essentially excellent resolution, and is used in production of precise original patterns.
FIG. 28 is a conceptual diagram for explaining an operation of a variable-shaped electron beam lithography apparatus. The variable-shaped electron beam (EB: Electron Beam) lithography apparatus operates as described below. A rectangular opening 411 to form an electron beam 330 is formed in a first aperture plate 410. A variable-shaped opening 421 to shape the electron beam 330 having passed through the opening 411 of the first aperture plate 410 into a desired oblong shape is formed in a second aperture plate 420. The electron beam 330 shone from a charged particle source 430 and having passed through the opening 411 of the first aperture plate 410 is deflected by a deflector and passes through a portion of the variable-shaped opening 421 of the second aperture plate 420 before being shone on a target object 340 placed on a stage continuously moving in a predetermined direction (for example, the X direction). That is, a rectangular shape capable of passing through both the opening 411 of the first aperture plate 410 and the variable-shaped opening 421 of the second aperture plate 420 is written in a pattern writing region of the target object 340 placed on the stage continuously moving in the X direction. The method of forming any shape by causing a beam to pass through both the opening 411 of the first aperture plate 410 and the variable-shaped opening 421 of the second aperture plate 420 is called the variable-shaped beam method (VSB method).
In electron beam pattern writing, dimensional variations caused by mask processes or an unknown mechanism are resolved by adjusting a dose of an electron beam. Conventionally, a correction model is set and an operation to correct the dose based on the model is performed inside the lithography apparatus and the dose is controlled in accordance with the operation result inside the lithography apparatus. For example, the proximity effect correction operation can be cited. However, even if the dose calculated inside the lithography apparatus is used, a correction residual may remain. Particularly, there is a case when the dose should be additionally controlled for a partial pattern or a local region, separately from other patterns or regions. In such a case, the modulated dose needs to be set by a user or correction tool or the like before data is input into the lithography apparatus. However, if the value set by the user or an operation result by the correction tool is incorrect, such a value is input into the lithography apparatus and the value is used by the lithography apparatus, causing a problem of irradiation of a beam of an abnormal dose. The beam irradiation of such an abnormal dose causes abnormalities of pattern dimensions CD. Further, if the dose is an extremely abnormal value, resist evaporation and by extension, lithography apparatus contamination (or a lithography apparatus failure) could be caused by such evaporation.